The present application claims priority to European Patent Application Serial No. 00830714.2-2301; filed Oct. 30, 2000.
1. Field of the Invention
The present invention relates to a shut-off valve for pressurized fluids in an air cooling/heating system such as air conditioners and the like.
2. Background of the Invention
It is known in the art of air conditioners and heat pumps that a condenser and an evaporator must be placed in communication with each other by means of shut-off valves and other devices designed to cause expansion of the refrigerant as the refrigerant flows from one component to another.
Specifically, in refrigerant systems operating in both the cooling and heating modes, two expansion devices may be incorporated into one system allowing for expansion of the fluid in either direction. A shut-off valve may also be incorporated into a system when there is a need to terminate refrigerant flow, such as for example, during servicing. The refrigerant system may also include a sampling port for detecting and measuring the pressure of the high-pressure refrigerant before the refrigerant enters the expansion device. Furthermore, the ability to easily interchange the expansion device allows the degree of expansion to be selectively varied after installation of the shut-off valve.
Combining the shut-off valve, expansion devices and sampling device into one unit is desirable to reduce the complexity of a refrigerant system. However, known refrigerant systems lack a mechanism for sampling the liquid refrigerant before the liquid enters the expansion devices in both the cooling and heating modes. Therefore, a need exists for a shutoff valve that allows for sampling high-pressure liquid between two expansion devices.
The present invention resolves the above noted problem by providing a mechanism that permits sampling of fluid refrigerant before expansion in either the cooling or heating mode. In particular, a shut-off valve is disclosed that includes at least two ducts. A first duct is positioned in communication with an evaporator. A second duct is positioned in communication with a condenser. Preferably, a third duct is adapted for receiving an instrument for sampling the fluid. A restrictor is arranged within the first and second ducts wherein each restrictor is formed with a capillary through which fluid passes and which causes rapid expansion of the fluid when the fluid exits from the capillary. Each restrictor is confined to an area defined by a cartridge and the body of the valve allowing limited axial movement of the restrictor in the direction of the fluid flow.
In accordance with the preferred embodiment, an insert member retains a cartridge in the first duct. The insert member is preferably retained by a flared nut threaded onto an externally threaded end of the first duct thereby clamping a flared end of a pipe directly against a conical surface of the insert member forming a seal. A cartridge in the second duct is preferably retained by a pipe received in a counterbore created between the second duct and the cartridge. The pipe is fixedly attached to the body of the valve by brazing or other suitable means of attachment.
In operation, the pressurized fluid flows from duct one to duct two in the heating mode and from duct two to duct one in the cooling mode. The valve is arranged such that duct three, or the duct receiving the sampling instrument, is positioned between ducts one and two. In this arrangement, the instrument may measure the pressure of the fluid as it flows between duct one and duct two. The shut-off valve arrangement is advantageous because it allows the fluid to be sampled before expansion in either the heating or cooling mode.
In accordance with a second embodiment, each cartridge is retained by a pipe received in a counterbore created between each cartridge and the corresponding duct. The pipe is fixedly attached to the body of the valve by brazing or other suitable means of attachment. A brazed pipe connection is advantageous because it requires fewer elements than a flared pipe connection.
In accordance with a third embodiment, an insert member retains each cartridge in both the first and second ducts. Each insert member is retained by a nut threaded onto an externally threaded end of each duct thereby clamping a flared end of a pipe directly against a conical surface of the insert member forming a seal. A flared pipe connection is advantageous because the connection can be disassembled allowing the substitution of a restrictor with a different capillary diameter. The ability to interchange a restrictor allows the shut-off valve to be field serviced without the need for complex brazing operations.